Minnesota Vikings quarterback Christian Ponder addresses supporters during a rally in the rotunda of the State Capitol, where the Minnesota House was taking up a bill for a new stadium for the NFL football team Monday, May 7, 2012, in St. Paul, Minn.

King Banaian is a rare specimen. First off, he’s a professor from St. Cloud State University in Minnesota who teaches a course on sports economics. So he’s plenty familiar with one of the rare economic argument that almost everyone in his field can agree on: the public benefits of sports facilities don’t outweigh the public cost.

But Banaian is also a state politician, a Republican member of Minnesota’s House of Representatives. So he now has a chance to apply his ivory-tower research to the real world, as the state is embroiled in an emotional battle to keep its pro football team, the Vikings, in Minnesota. The owner of the Vikings, Zygi Wilf, has been clamoring for the state and the city of Minneapolis to help build the team a new stadium to replace the aging Metrodome. (The Vikings have been playing in the Metrodome since 1982; remember that time the roof collapsed before a game?) Without a new stadium, Wilf may move the team. His jet was recently spotted in Southern California; Los Angeles hasn’t had an NFL team since 1994, which is quite incredible, given that LA is the second biggest market in the U.S.

On Monday, the Minnesota House passed a bill in which the state and city governments would kick in $443 million — a major chunk of public change — while the Vikings and the NFL would pick up the rest of the $975 million tab. Banaian voted against the bill, which has moved on to the Minnesota Senate. “If I didn’t, I’d be betraying my core principles,” Banaian says from his legislative office in St. Paul. “I’m going to be an economist much longer than it’s politically expedient.”

It’s a good thing Banaian can fall back on the classroom, because he won his district by a mere 13 votes back in 2010. Voting against the Vikings is no way to win friends in Minnesota, and neither is his fan allegiance — the New York Giants are his favorite team. “I’ve gotten some emails from friends, asking, ‘Are you hearing what they are saying about you on sports radio?'” Banaian says. “‘They’re saying I should enjoy my time down here, because it’s not going to last much longer.'”

But Banaian has run the numbers, and believes the $443 million public cost is too prohibitive, especially in a down economy. Minnesota governor Mark Dayton, a Democrat, says stadium construction will deliver 8,000 jobs: Banaian estimates that the project will add 2,000-2,500 jobs. Economic study after economic study has shown that the promises of stadium windfalls don’t come true. One major reason is the substitution effect: if people don’t spend their discretionary dollars on season tickets and hot dogs and parking and other costs associated with attending sports events, they’ll spend it on other activities and businesses within a metropolitan area (the movies, the car dealership, restaurants). Or maybe individuals will — gasp — save that Vikings money, which might not help local GDP in the short-term, but could greatly benefit an individual down the road.

Banaian predicts that the Vikings will get their new stadium, with a significant public contribution, if for no other reason that politicians are tired of talking about the issue and want to move on. “The vote will probably pass on stadium fatigue alone,” Banaian says.

For his part, Banaian is itching to get back to St. Cloud, which is 65 miles northwest of Minneapolis, to start teaching another sports economics course at the end of the month. He starts the first class by showing a famous scene from the movie Field of Dreams: a voice tells Kevin Costner in his Iowa cornfield that “if you build it” — a baseball field — “he will come.” Banaian then spends the rest of the course tearing down Field of Dreams mythology (remember all those car headlights lined up in the Iowa night, once Costner’s character did build that field?). After all, if you build it, they might not come.

“Boy,” says Banaian, talking about his stadium class, “I have some new material now.”